What I see is a definite separation between types of media.
Print media and government-subsidized broadcasters rank near the top of the list. Internet sources are near the bottom, with commercial national networks not far behind. So, a left-wing rag like The Guardian can get high remarks for trustworthiness, while Yahoo!, which doesn't have a lot of original content and generally simply republishes newspaper and wire articles, gets seen as untrustworthy.
It's interesting to note that supermarket tabloids like the National Enquirer are not included in the survey, perhaps intentionally to avoid exposing a glaring pro-print bias.